1. Technical Field
The present invention relates in general to an improved hard disk drive design and, in particular, to an improved design for a hard disk drive having a screw attachment from outside the enclosure for motors with a mount bracket screw bolt pattern diameter that is larger than the motor hub outside diameter.
2. Description of the Related Art
Generally, a data access and storage system consists of one or more storage devices that store data on magnetic or optical storage media. For example, a magnetic storage device is known as a direct access storage device (DASD) or a hard disk drive (HDD) and includes one or more disks and a disk controller to manage local operations concerning the disks. The hard disks themselves are usually made of aluminum alloy or a mixture of glass and ceramic, and are covered with a magnetic coating. Typically, one to six disks are stacked vertically on a common spindle that is turned by a disk drive motor at several thousand revolutions per minute (rpm).
A typical HDD also utilizes an actuator assembly. The actuator moves magnetic read/write heads to the desired location on the rotating disk so as to write information to or read data from that location. Within most HDDs, the magnetic read/write head is mounted on a slider. A slider generally serves to mechanically support the head and any electrical connections between the head and the rest of the disk drive system. The slider is aerodynamically shaped to glide over moving air in order to maintain a uniform distance from the surface of the rotating disk, thereby preventing the head from undesirably contacting the disk.
Typically, a slider is formed with an aerodynamic pattern of protrusions on its air bearing surface (ABS) that enables the slider to fly at a constant height close to the disk during operation of the disk drive. A slider is associated with each side of each platter and flies just over the platter's surface. Each slider is mounted on a suspension to form a head gimbal assembly (HGA). The HGA is then attached to a semi-rigid actuator arm that supports the entire head flying unit. Several semi-rigid arms may be combined to form a single movable unit having either a linear bearing or a rotary pivotal bearing system.
The head and arm assembly is linearly or pivotally moved utilizing a magnet/coil structure that is often called a voice coil motor (VCM). The stator of a VCM is mounted to a base plate or casting on which the spindle is also mounted. The base casting with its spindle, actuator VCM, and internal filtration system is then enclosed with a cover and seal assembly to ensure that no contaminants can enter and adversely affect the reliability of the slider flying over the disk. When current is fed to the motor, the VCM develops force or torque that is substantially proportional to the applied current. The arm acceleration is therefore substantially proportional to the magnitude of the current. As the read/write head approaches a desired track, a reverse polarity signal is applied to the actuator, causing the signal to act as a brake, and ideally causing the read/write head to stop and settle directly over the desired track.
One example of a prior art disk drive configuration is shown in FIG. 6. The screws 17 which secure the bracket 15 to the base 19 are located inside the seal 16 and, thus, contaminants from the screws 17 remain inside the disk drive 11. Moreover, as shown in this relatively high platter count disk drive 11, the bottom disk 13 is positioned very close to the motor bracket 15 and the screws 17 that mount the bracket 15 to the base 19. Furthermore, if the space between the disk 13 and the surface of the bracket 15 is small, the air drag can increase drastically and thereby impede the performance of the disk drive.
Another example of a prior art disk drive configuration is shown in FIG. 7. Although the single screw 27 is mounted on an exterior of the base 29 to bracket 25 and a seal 26 (such as an O-ring) can prevent contamination from screw 27, the configuration of the support portion of base 29 is required to be below the entire bracket 25 and, therefore, the available internal space in the disk drive housing is significantly reduced for the stator/winding. Thus, an improved design for mounting a hard disk drive motor to an enclosure thereof would be desirable.